Contingency ranking with respect to overloads in very large power systems taking into account uncertainty, preventive, and corrective actions

in IEEE Transactions on Power Systems (2013)

This paper deals with day-ahead security management with respect to a postulated set of contingencies, while taking into account uncertainties about the next day generation/load scenario. In order to help ... [more ▼]

This paper deals with day-ahead security management with respect to a postulated set of contingencies, while taking into account uncertainties about the next day generation/load scenario. In order to help the system operator in decision making under uncertainty, we aim at ranking these contingencies into four clusters according to the type of control actions needed to cover the worst uncertainty pattern of each contingency with respect to branch overload. To this end we use a fixed point algorithm that loops over two main modules: a discrete bi-level program (BLV) that computes the worst-case scenario, and a special kind of security constrained optimal power flow (SCOPF) which computes optimal preventive/corrective actions to cover the worst-case. We rely on a DC grid model, as the large number of binary variables, the large size of the problem, and the stringent computational requirements preclude the use of existing mixed integer nonlinear programming (MINLP) solvers. Consequently we solve the SCOPF using a mixed integer linear programming (MILP) solver while the BLV is decomposed into a series of MILPs. We provide numerical results with our approach on a very large European system model with 9241 buses and 5126 contingencies. [less ▲]

Operating in the fog: security management under uncertainty

in IEEE Power & Energy Magazine (2012)

On simplified handling of state events in time-domain simulation

in Proceedings of the 17th PSCC (2011, August)

The power system models typically used in dynamic simulations involve discrete events in addition to the standard differential-algebraic equations. Those events cause the system to jump from one ... [more ▼]

The power system models typically used in dynamic simulations involve discrete events in addition to the standard differential-algebraic equations. Those events cause the system to jump from one continuous behavior to another. Solvers have to handle those jumps. This paper focuses on simplified time simulation where large steps are used in conjunction with stiff-decay integration methods to obtain approximate solutions in short computing times. In the proposed simulation scheme, the simulation time steps are not synchronized with the system jumps, which are treated a posteriori in a corrective step. In this context, the paper analyzes several simple nonlinear models involving limiters, switches, minimum gates, etc. from which some precautions to be taken at the modelling and solving stages are stressed. The paper also reports on results obtained with a representative power system model. [less ▲]

Consequence driven decomposition of large-scale power system security analysis

in Proceedings of the 2010 IREP Symposium - Bulk Power Systems Dynamics and Control - VIII (2010, August)

This paper presents an approach for assessing, in operation planning studies, the security of a large-scale power system by decomposing it into elementary subproblems, each one corresponding to a ... [more ▼]

This paper presents an approach for assessing, in operation planning studies, the security of a large-scale power system by decomposing it into elementary subproblems, each one corresponding to a structural weak-point of the system. We suppose that the structural weak-points are known a priori by the system operators, and are each one described by a set of constraints that are localized in some relatively small area of the system. The security analysis with respect to a given weak-point thus reduces to the identification of the combinations of power system configurations and disturbances that could lead to the violation of some of its constraints. We propose an iterative rare-event simulation approach for identifying such combinations among the very large set of possible ones. The procedure is illustrated on a simplified version of this problem applied to the Belgian transmission system. [less ▲]